The short answer is that any vote that preferentially effects one class over another requires vote by class. All effected classes must vote yes.
The longer answer is that the NWBO Articles of Incorp. give blank check auth to the BOD to define voting rights when creating a class via the Cert of Designation. And in this case the Cert says the pref votes with the common unless not allowed under DE law. And the only DE law override is what I stated above.
I think this is really a minor point. LP can already control things anyway. Perhaps the revers is more likely, this precludes LP from having to worry about a small group who might vote against her.
Appreciate the link to the proxy statement - a quick perusal suggests it will be worthwhile cutting through the tangle of legelese, after I get my caffeine levels up.